This invention relates to a dust mop provided with an electrostatically charged thermoplastic fabric (dust collector) for attracting dust particles such as those commonly found in households. In one aspect it relates to a mop having a charged nonwoven thermoplastic fabric detachably secured to the mop head, wherein the charges in the fabric attract and hold dust particles. In a more specific aspect, it relates to a dust mop having an electrostatically charged meltblown fabric which is detachably secured to the mop head by electrostatic cling.
As is widely known, the activity of dusting to remove unwanted and/or unsanitary dust particles is a common household or office task. In many situations the task can be accomplished with a dust rag and a simple wipe-of-the-hand. There are, however, many other situations where the task becomes more complicated. These include hard-to-reach places such as around floorboards, the upper portion of a walls and ceilings, on floors such as hardwood floors, and ceiling fans.
The present invention provides a dust mop that which not only facilitates dusting in difficult areas but has a dust collector that can be changed easily. As described in detail below, the dust collector of the mop is made of electrostatically charged nonwoven fabric. A brief description of the more important nonwoven fabrics may be helpful: meltblowing and spunbonded fabrics.
Meltblowing is a process wherein a molten polymer is extruded through a meltblowing die to form a plurality of side-by-side fibers. Convergent sheets of air are directed onto opposite sides of the fibers as they leave the die. The air draws and attenuates the fibers to microsized diameters (viz. 0.05-15 microns). The fiber and air stream is directed onto a moving collector surface where the fibers deposit in a random pattern and form a nonwoven fabric or web. The fabric is held together primarily by interfiber entanglement with some fiber sticking while in the molten or semi-molten state. The fibers may be continuous or discontinuous filaments. By varying operating conditions, meltblown fabrics having different basis weights may be produced.
It is well-known in the art of meltblowing to apply an electrostatic charge to the fibers as they are extruded or, alternatively, after the fabric is formed. Electrostatically charged meltblown webs are often referred to as electrets. Electrets were originally developed for gas filtration applications wherein the charges act to attract particulate matter that flows through the web. Since most nonwoven webs are dielectrics, the charge is very persistent and may be sustained for periods of a year or longer. U.S. Pat. Nos. 4,215,682 and 4,904,174 disclose apparatus for producing electrets by the "hot charging" method as well as test data indicating the filtration efficiency of the webs. PCT application PCT/US/93/09630, and its U.S. counterpart U.S. Pat. No. 5,401,446, disclose "cold charging" methods and apparatus for producing electrets.
Spunbonded fabrics are nonwoven fabrics that are produced by extruding a molten polymer through a spinneret that is a metal disc or die containing numerous minute holes through which the polymer is forced. Continuous filaments are extruded through the spinneret and are blown by low velocity air and deposited on a moving foramenous conveyer. The desired orientation of the filaments in the web are achieved by rotating the spinneret, by electrical charges, by controlled airstreams, and by the speed of the conveyer. The web can be additionally bonded by passing through compacting rolls and/or hot-roll calendering. Spunbonded webs generally have larger average diameter filaments (viz. 10-100 microns, typically 20 to 60 microns) than meltblown webs and, therefore, tend to be heavier and stiffer. Spunbonded webs can be electrostatically charged by methods described in U.S. Pat. Nos. 4,592,815; 4,375,718; and 5,401,446.
A paper presented at "Fiber Producer Conference 1983", in Greenville, S.C. entitled "Nonwoven Fabrics: Spunbonded and Meltblown Processes" describes the two processes in detail. The disclosures of this paper and the above noted patents are incorporated herein by reference.